Carbureter.



H. McCORNACK.

CARBURETER,

APPLICATION FILED AUG.I5. I910.

1,141,570 Patented June 1, 1915.

3 SHEETSSHEET l- H. McCORNACK.

CARBURETER.

APPLICATION FILED Aue.15. I910.

1 9 1, 4 1,570., Patented June 1, 1915.

3 SHEETSSHEET 2- C: 9. 734mm.

H. McCORNACK.

CARBURETER.

APPLICATION FILED AUG. 15, 1910.

Patented June 1, 1915.

3 SHEETS-SHEET 3- Ji fy/ 61 uisrr arrears raruur enrich.

HERBEBT MOCOR'NACK, OF WEST CHESTER, PENNSYLVANIA.

CARBURETEB.

Specification of Zetters Patent.

Patented June 1, 1915 Application filed August 15, 1910. Serial No. 577,144.

To all whom it may concern:

Be it known that I, HERBERT MCCORNACK, a citizen of the United States, residing at West Chester, in the county of Chester and State of Pennsylvania, have invented a new and useful Improvement in Carburetors, of

. which the following is.- a specification.

This invention relates to automatic carbureters of the type which are used for supplying the fuel to internal combustion engines level; of the liquid fuel in the carbureter due .to changes .in the position of the latter, as when usedv on motor vehicles; also to ac-.

complish these results without the employ-- ment' of, mechanically; operated devices and without the necessity for accurate adjustments; also to separate thev excess unvaporliquid fuel from the carbureted air and prevent it from being carried into the engine cylinder; also to return this unvaporized fuel to the incoming liquid fuel supply and cause it to be again discharged into the incoming current of air and to use the excess liquid fuel, separated from the mixture, to regulate or affect the liquid fuel supply; also to construct the carbureter so that the discharge orifice of the fuel supply nozzle can be made ofa size such that it will'not be, clogged or its action affected by particles of dirt or waterin the liquid fuel; also to effectually free the air from dust before carbureting it; and also to improve, the construction of carbureters in the respects hereinafter described and set forth in the claims.

These results are attained as follows: The carbureter is provided with a mixing chamberin which the mixture of air and liquid fuel is caused to whirl or rotate rapidly so that the excess fuel, or liquid which is not.

vaporized, will be thrown outwardly against the walls of the mixing chamber by centrifugal force and separated from the explosivemixture, which is taken axially out of the mixing chamber. The excess fuel thus separated from the air is returned to the fuel supply and again discharged into the air, the less volatile liquid, which is not readily vaporized, being in this way circulated and reused until it is finally volatilized. The walls of the mixing chum-bur are preferably heated and this heat s11 pple mented by the intimate frictional ontac of the rapidly rotating air in the mixing chamber with the less rapidly rotating film I of fuel on the Walls of the chamber insures a practically complete vaporization of the less volatile portions of the fuel which otherwise would not be vaporized. Thus while the air is thoroughly carbureted the unvaporized liquid is separated from the mixture with the result that the waste of fuel and the fouling of the cylinder is reduced to the minimum. .The excess liquid fuel separated from the air is preferably returned to the fuel supply nozizle so as to regulate or affect the supply of fuel to the carbureter, and in addition to this regulation, the fuel nozzle is constructed so that the suction produced by the engine operates to automatically regulate the resistance to the flow of the fuel through the nozzle in such a manner as to maintain a mixture of the proper I proportions of air and fuel under the varying demands of the engine. The carbureter is also provided with a centrifugal dust collector which thoroughly frees the air from dust before the air enters .the mixing chamber. The several features mentioned can be combined or arranged invarious ways to produce the results stated, so that the invention is not limited to the constructions of the carbureter illustrated in the drawings.

' In the accompanying drawings: Figure 1 is acentral sectional elevation of a carbureter embodying the invention. Fig. 2 is a plan view thereof on a reduced scale. Fig. 3 is a fragmentary plan viewv showing the air supply valve closed. Fig. 4 is a horizontal section on a reduced scale in line l -4, Fig. 1. Fig. 5 is a fragmentary sectional plan, on a reduced scale in line 5 5, Fig. 1. Fig. 6 is a fragmentary horizontal section on line 66, Fig. 1. Figs. 7 and 8 are horizontal sections, on a reduced scale, on lines 7 7 and 8'8, respectively, of Fig. 1. Fig. 9 is an enlarged section of the fuel supply nozzle and associated parts. Fig. 10 is=a fragmentary sectional elevation on line 10-10, Fig. 8. Fig. 11 is a fragmentary horizontal section on line 1111, Fig. 1. Fig. 12 is a section of a fuel supply nozzle of modified construction.

Like reference characters refer to like parts in the several figures.

A represents the outer'casing of the carbureter, B a reservoir or float chamber which contains the gasolene or other liquid fuel, C an air supply passage, D a carbureting or mixing chamber in which the liquid fuel discharged by a 'fuel supply nozzle E 1s mixed with the air, and F a discharge pipe or passage leading from the mixing chamber to the engine cylinder.

Preferably the mixing chamber D, which is circular in cross-section, is arranged concentrically within the casing A and forms therewith an annular chamber which constitutes the air supply passage C, to which the air is admitted through inlet openings 0 at the upper portion thereof. The float chamber B is located in the bottom of the casing below the mixing chamber, and the fuel supply nozzle extends from the float chamber axially into the lower end of the air supply passage which is of conical or funnel form. A reliminary carbureting or mixing chamber n? extends centrally up into the main mixing chamber D from the bottom thereof concentrically with the fuel nozzle and communicates by its 0 en lower end with the air supply passage and by openings in its side walls with the main mixing chamber. The discharge pipe connects axially with the top of the mixing chamber. The suction produced by the operation of'the engine draws the air through the air supply passage C past the fuel supply nozzle and up through the preliminary mixing chamber the main mixing chamber.

Gdnto the main mixing chamber D. The fuel which is drawn from the fuel nozzle E by the suction ofithe a1r is vaporized and mixed with the air in the preliminary and main mixing chambers to produce the explosive mixture, which passes to the engine through the discharge pipe 1 Means are provided for causing the air to whirl or rotate rapidly in the funnel-shaped lower end of the air supply passage about the discharge orifice of the'fuel supply nozzle and also in This concentric arrangement of the parts is especiallysuited to a carbureter embodying the invention,

makes the carbureter compact and facilitates tlici it tnanufacture thereof. The invention is not, however, restricted ta such concentric 'arrangement of the parts as will hereinafter cupped shell a having a tapering or conical bottom and fitting tightly in the open lower end of the upper shell, and a lower cupped shell a. fitting tightly on the lower end of the intermediate shell. The float chamber in s formed by the lower shell .a? nd the 1 bottom of the intermediate shell.

The supply of liquid fuel is controlled to maintain the required liquid level in the float chamber, as usual, by a suitable valve 6 in the fuel supply pipe I) actuated by a float 6 through levers b or other connections.

The mixing chamber D, which is cylindrical or of circular cross-section, is formed by upper and lower cupped shells d d arranged with their meeting open ends fitting tightly one withinthe other. The bottom of the mixing chamber is tapered correspondingly with the bottom of the intermediate shell of the outer casing whereby the lower end of the annular air supply passage converges downwardly toward the fuel noz-' zle E. The upper portion of the mixing chamber D is preferably surrounded by a jacket d through which the engine exhaust, or other heating medium, is circulated for heating the walls of the mixing chamber. This jacket is formed by an upper enlarged end (i of the lower shell 03 of the mixing chamber and a cupped shell (2* fitting tightly therein, and is provided with nipples d for connection with circulating pipes for the heating medium.

The fuel discharge nozzle, see Fig. 9, is screwed into a flanged nut or collar 6 and has a flange e at its lower end which engages an internal shoulder e on a tube a which surrounds the nozzle in the float chamber. By screwing the nozzle into the collar 6 the edge of the opening in the bottom of the air supply passage through which the nozzle projects is clamped between the flange of the collar 6 and the upper end of the tube a whereby the nozzle is securely held. The operating levers b for the fuel supply valve 6 are fulcrumed in slots in the tube a The lower end of the tube 6 extends through the bottom of the float chamber and has a nipple or connection e for the fuel supply pipe screwed thereon, the joint between this nipple and the bottom of the float chamber being suitably packed to prevent leakage from the float chamber. The discharge pipe F is provided with a throttle valve f of any suitable construction.

The preliminary carbureting or mixing chamber G is formed by a cupped shell 9 which communicates by its open lower end with the air supply passage and by openings 9' in its sides with the main carbureting or mixing chamber D. The lower end of the shell 9 is connected to the bottoms of the mixing chamber and of the air supply passage G, as by an enlarged or shouldered part 9 on which the bottom of the mixing chamber bears, and by fastening tongues 57 which pass through slots in. the bottom of the air passage and are clenched on the underside thereof; and a central stay rod or bolt 9 secured to the upper end of the shell 9 extends up through the discharge pipe F and is provided at its upper ".end

provided at its top with a collar 9 which fits in the lower end of the discharge pipe F, and the upper ends of the shells forming the outer casing and the heating jacket d? are clamped between the top of the mixing chamber and the end of the discharge pipe, so that by tightening the nut g the shells of the outer casing, the mixing chamber D and the heating jacket are drawn tightly together and firmly held in place. By thus 7 makingthe parts of complementary cupped and mixing it with the air.

shells they can be formed by drawing from sheet metal, which lessens the cost of manufacture of the carbureter, and when the stay rod 9 is released the parts can be readily separated, thus affording access to the interior thereof. This construction is there fore desirable, but any other suitable construction of the parts and means for connecting them can be employed.

The rotation of the air about the fuel nozzle is preferably caused by oblique or tangential vanes H which surround the nozzle in the funnel-shaped lower end of the air supply passage C and are conveniently formed by slitting the lower end of the shell g of the preliminary mixing chamber and bending portions thereof obliquely in- Ward.

The movement of the air through the converging or funnel-like lower portion of the air passages produces a concentration or pressure thereof which increases as the air approaches the fuel nozzle and this pressure of the air, together with the rapid rotation of the air due to the oblique vanes H, causes a cyclone-like action causing a suction about the discharge orifice of the nozzle which draws the liquid fuel from the nozzle and violently agitates it in the preliminary mixing chamber, thus breaking it up very finely The air and atomized fuel pass from the preliminary mixing chamber through the openings 9' and are delivered tangentially into, and are caused to continue rotating in the same direction in the main mixing chamber D by curved vanes or plates I which extend outwardly and forwardly in the main mixing chamber from the rear edges of the openings g in the walls of the preliminary mixing chamber. These vanes or plates I, in the construction shown, are held between the bottom of the main mixing chamber and a cap plate 2' which is secured on the top of the preliminary mixing chamber by the stay rod 9, and they have securing extensions at their inner ends which bear against the walls of the preliminary mixing chamber and are confined by flanges or portions 2" and i of the cap 71 and the bottom of the main mixing chamber surrounding their upper and lower ends.

The rapidly rotating mixture in the mix- -1ng chamber D causes the unvaporize liquid fuel to be thrown outwardly agains the cylindrical wall of the chamber where it spreads and rotates with great velocity. The carbureted air having the unvaporized liquid fuel thus eliminated, is displaced inwardly and 'drawn off through the axial discharge outlet F. The unvaporized liquid fuel being thus detained, rotates with great velocity upon the wall of the cylinder and is forced to fiow through opening K into the passage k by whichit is returned to the fuel supply by means of the following factors: The driveor centrifugal action of the liquid as it rotates upon the wall of the mixing chamber, gravity, a lower pressure at the nozzle than that of the mixing chamher due to the drive or injector action of the air at its orifice, and the injector action of the incoming liquid supply in the nozzle.

As shown in Figs. 1 and 10, the return pipe connects with an annular channel '70 which surrounds the nozzle B and is connected by a passage 10 with the discharge orifice of the nozzle, so that the fuel nozzle acts by the injector action to draw the fuel partly from the float chamber and partly from this returned excess supply. The dis charge of new fuel from the fioat chamber B is therefore regulated or affected by the quantity of excess fuel returned from the mixing chamber to the fuel supply nozzle. By thus separating the unvaporized liquid fuel from the explosive mixture and returning it to the supply to be again used, the dis charge orifice of the nozzle can be made large enough to supply the requisite fuel for the maximum quantity of explosive mixture demanded by the engine and the fuel will not be wasted or the cylinder fouled if the quantity of fuel supplied is in excess of what is needed under the varying running conditions. As the cylindrical wall of the mixing chamber is heated and the excess fuel is circulated and repeatedly subjected to this heat and to the frictional contact of the rapidly rotating mixture in the mixing chamber, the vaporization of the fuel is practically complete.

In order to regulate the supply of fuel in accordance with the supply of air so as .to maintain an explosive mixture of substantially the same proportions of air and fuel for all suctions, the fuel nozzle E, in the construction shown in Figs. 111, is provided with a tangential inlet orifice L, see Fig. 11. The tangential inlet causes the liquid fuel to rotate in the chamber or bore Z of the nozzle from which the fuel escapes through the axial discharge orifice. This construction of the nozzle compensates for the difference in the laws which control the the gasolene in a tube is proportional to the difference in pressures at the two ends of the tube. The flow of air in a carbureter is, however, governed by a different law, as air flowing from a source at one pressur into a receiver at a lower pressure expan ti and a portion of the energy which produces the flow is used in producing this expansion. The flow of air is consequently proportional to the square root of the difference between the squares of the absolute pressures of the outside atmosphere and of the air in the carbureter at the discharge orifice of the fuel nozzle. If the area of the air opening under various suctions, which is obviously the measure of the resistance, is proportional to the square of the suctions, the correct proportioning of the explosive mixture for all suctions is obtained.

Since the rotation of the liquid in the cylindrical bore of the nozzle is proportional toithe flow of the liquidthrough the bore and the centrifugal force of the rotating liquid is as the square of the revolutions, the described construction of the nozzle causes a resistance to the flow of the liquid through the discharge orifice which is as the square of the flow, and inasmuch as the flow is pro-.

portional to the suction, the resistance to the liquid flow is proportional to the square of the suctions. As this centrifugal factor in the liquid flow compensates for the re sistance to the flow of the air due to expansion, the expansion being as the square of the suction, the proper proportions of the air and fuel in the explosive mixture are maintained for all suctions by .the described construction of the fuel nozzle E. A similar action can also be secured by other constructions. For instance, the nozzle can be provided with a helical fiow passage Z formed by a helically threaded core-in the nozzle bore, as shown in Fig. 12. This compensa- .tion does not, however, apply to capillary or skin resistance to the flow of the two elements. As the capillary resistance to the flow of the liquid fuel is lessened by increasing the size of the nozzle passage, the centrifugal resistance to, the flow of the liquid has another advantage in that it makes it possible "to use a larger flow passage through the fuel nozzle. The nozzlev orifice can be made so large that it will not be clogged or affected by dirt or water in the fuel, which is a great source of trouble in many carbureters inwhich the discharge orifice of the fuel supply nozzle must be very small. With the excess fuel returning through the nozzle as explained, and provisionfor creating the centrifugal resistance, a discharge orifice of over one-sixteenth of an inch in diameter has been successfully used. I

M represents the centrifugal dust collector, which preferably surrounds the upper portion of the air supply passage or chamher 0 and comprises an annular separating chamber m and an annular dust chamber or pocket m below the separating chamber. The separating chamber is provided at its upper outer portion with air admission openthis chamber and passes through holes m I therein into the dust chamber m which has dust discharge holes m which are normally closed by a valve or ring at and are adapted to be opened to discharge the dust by turning said ring. The inlet openings 0 to the air supply passage are preferably covered by a screen which aids in the separation of the dust. The air rotating in the separating chamber outside of the screen prevents the dust from collecting thereon and clogging the screen as it is apt to do in the case of a simple filtering screen.

I The dust collector is preferably constructed as shown, the separating chamber being formed by an inverted cupped shell m inclosing the upper end of the carbureter casing and a cupped ring m fitting in the shell, 95

and the dust chamber being formed by an outwardly projecting flange m at the lower end of the top shell of the casing and the cupped valve ring which rests on said flange m and fits loosely on the enlarged lower end of the shell m The shell m, like the upper shells of the casing A, and the heating jacket are held between the top of the mixing chamber D and the lower end of the discharge pipe F.

on is a valve which fits loosely on the top of the dust collector and has holes m adapted to register with the air admission openings m and is provided with a handle m for turning it. By adjusting this valve the air supply to the carbureter can be regulated as required.

The described construction of the dust collector is desirable as the parts thereof can all be made by drawing from sheet metal, and the concentric arrangement of the dust collector around the casing is well adapted to a carbureter such as described, in which the air is caused to rotate in the air supply passage and mixing chamber, and makes the carbureter compact, but other constructions and arrangements of the dust collector could be used.

I claim as my. invention:

1. In a carbureter, the combination of air supply means, a liquid fuel supply nozzle, a carbureting chamber located close to said fuel nozzle and into which said fuel and air "are directly discharged and in which the air cular wall and being provided with nondriven means for causing the air and fuel to rotate therein and with an outlet, for the explosive mixture which is located inwardly from said circular wall whereby the unvaporized liquid is thrown outwardly against said circular wall and is trapped in the car bureting chamber, and a normally open passage which leads from said chamber to said nozzle and through which the unvaporized liquid flows from the carbureting chamber back to said fuel supply nozzle, substantially as set forth.

2. In a carbureter, the combination of air supply means, a liquid fuel supply nozzle, a carburetingv chamber in which the air is carbureted by contact with the liquid fuel having a circular wall and provided with stationary members for causing the air and fuel to rotate therein and with an outlet for the explosive mixture which is located inwardly from said circular wall whereby the unvaporized liquid is thrown outwardly against said circular wall and is trapped in the carbureting chamber, and a normally open passage leading from said chamber to said nozzle for returning said unvaporized fuel to the fuel supply nozzle, substantially as set forth.

3. In a carbureter, the combination of air and-liquid fuel supply means, a carbureting chamber of circular cross-section, means for causing the mixture of air and fuel to rotate in said carbureting chamber for separating the unvaporized liquid from the mixture, and means for regulating the fuel supply by the separated liquid, substantially as set forth.

4. In a carbureter, the combination of air and liquid fuel supply means, means for separating the unvaporized liquid from the mixture of air and fuel, and means for regulatin the fuel supply by the separated liquid, su stantially as set forth.

5. In a carbureter, the combination of a main liquid fuel supply means, air supply means, means for separating the unvaporized liquid from the mixture of air and fuel, and means for returning the separated liquid to the fuel supply means for regulating the supply of fuel from said main supply means, substantially as set forth.

6. In a carbureter, the combination of air supply means, a liquid fuel supply nozzle, a carbureting chamber having a tangential inlet and an axial outlet whereby the air and fuel are caused to rotate in said carbureting chamber and the unvaporized fuel is separated from the mixture, and means for returning the separated liquid to the fuel supply nozzle for regulating the discharge of new liquid therefrom, substantially as set forth.

7. In a carbureter, the combination of air supply means, a liquid fuel supply nozzle,

means for separating the unvaporized liquid from the mixture of air and fuel, and means for returning the separated liquid to the discharge passage of said nozzle whereby the nozzle acts by the injector action to discharge said separated liquid, substantially as set forth.

8. In a carbureter, the combination of air and liquid fuel supply means, a carbureting chamber of circularcross-section, and means for causing the mixture of air a'ndfuel to rotate in said carbureting chamber for separating the unvaporized liquid from themixture, means for returning the separated liquid'to the fuel supply means, and means for heating the circular wall of said carbureting chamber, substantially as set forth.

9. In a carbureter, the combination of a carbureting chamber, means for causing the mixture to whirl therein, a liquid fuel supply nozzle located axially with reference to said carbureting chamber, a converging air supply passage and deflecting members by which the entire air supply is delivered toward said nozzle in adirection opposed to the direction of discharge from the nozzle and is caused to rotate about the discharge orifice of the nozzle, substantially as set forth;

10. In a carbureter, the combination of a carbureting chamber, means for causing the mixture to whirl therein, a liquid fuel sup- .ply nozzle located axially with reference to said carbureting chamber, an air supply passage having a funnel-shaped portion which converges toward said nozzle in a direction opposite to the direction of discharge of said nozzle, and means for causing the air to rotate in said converging portion of the air supply passageabout said nozzle, substantially as set forth.

11. In a carbureter, the combination of a liquid fuel supply nozzle, an air supply passage having a funnel-shaped portion which converges toward said nozzle, and vanes arranged tangentially in said converging portion of the air supply passage around the nozzle for causing the air to rotate about the nozzle, substantially as set forth.

12. In a carbureter, the combination of a fuel supply nozzle, an air supply passage, a cylindrical chamber having a tangential ,inlet and an axial outlet, and a preliminary carbureting chamber arranged within and through which the air and fuel pass to said cylindrical chamber, substantially as set forth.

13. In a carbureter, the combination of a fuel supply nozzle, an air supply passage having means for causing the air to rotate therein about said nozzle, a cylindrical chamber having a tangential inlet and an axial outlet, and a preliminary carbureting chamber arranged concentrically with said nozzle and through which the air and fuel pass to said cylindrical chamber, substan- .tially as set forth.

14. In a carbureter, thecombination of a carbureting chamber arranged concentrically therein and forming an annular air supply passage, a fuel supply nozzle arranged axially at one end of said passage, tangen: tial vanes in said passage around said noz located in said air passage axially with respect to said preliminary carbureting chamber,;vanes in said air supply passage for causing the "air' to rotate about said fuel supply nozzle, and vanes extending from said preliminary carburetingtachamber into said circular chamberffo ea'using the air and fuel to rotate in said ircular chamber, substantially asset forth 1 16. In a carbureter, the. combination of a carbureting chamber, means for, causing the mixture to whirl therein, an axial outlet, a fuel supply nozzle, an airsuplply passage surrounding said carbureting chamber, and.

a heating jacket surrounding said carbureting chamber in said air supply passage,

substantially asset forth.

17. In a carbureter, the combination of a carbureting chamber of circular cross-section, a fuel supply nozzle, a heating jacket surrounding said carbureting ffchamber, an air supply passage surrounding said heating jacket, and means for causing the air and fuel to rotate in said carbureting chamber. substantially as set forth.

18.. In a carbureter, the combination with fuel" supply means, of a dust collector through which the air passes to the carbureter and which is provided with means for causing the air to rotate therein, and means for causing the air to continue in rotation in the same direction in the carbureter, substantially as set forth.

19. In a carbureter, the combination with fuel supply means, of a dust collector through which the air passes to the carbureter and which is arranged concentrically with respect to the carbureter and is provided with means for causing the air to rotate therein, and means for continuing the rotation of the air in the carbureter, substantially as set forth.

21; In a carbureter, the combination with.

fuel supply means, a carbureting chamber in which the air'andfuel arecaused torotate', of a dust collectonthrou'gh which the. air

passes to the carbureting chamber having an annular separating chamber surrounding said carbureting chamber and provided with an air inlet disposed so as to cause the air to rotate therein andwith an air outlet in its inner wall, substantially as set forth.

22. In a carbureter, the combination with fuel supply means, and an air passagejin which the air is caused to rotate, of a dust collector through which. the air passes to the carbureter havingan annular separating chamber arranged concentrically with re-, spect to the carbureterand provided with means for causing the air to rotate therein and with an air outlet leading to said-air passage, substantially as set forth.

23. In a carbureter, the combination with Y fuelsupply means, and an air supply passage of circular cross-section in hich the air rotates, of a dust collector through which the air passes to the carbureter sur rounding said air supply passage,said dust collector having means for causing thejair,

to rotate therein, and an air outlet iopening j in its inner wall leading to said air su ly passage, substantially as set forth.

- 24, Ina carbureter, the combination with fuel supply means, and a chamber of circular cross-section in which the .air is-caused to rotate, of a dustcollector through which the air passes to said circular chamber, com.- prising a separating chamber of circular cross-section having air inlets arranged to cause'the'air to rotate therein'and an air outlet located inwardly from the outer circumference of said chamber, and a valve controlling said air inlet openings which is adjustable to regulate the supply of air to the carbureter, substantially as set forth.

25. In a carbureter, the combination with fuel supply means, of a carbureting chamber of circular cross-section having means for causing the mixture to whirl therein, an air supply passage, and a heating jacket surrounding and concentric with said carbureting chamber, and a discharge pipe for the mixture arranged concentrically with respect to said carbureting chamber, and a stay rod which detachably secures said parts together.

26. In a carbureter, the combination with fuel supply means, a carbureting chamber of circular cross-section having means for causing the mixture to whir1 therein, an air supply passage concentnc with and surroun d- 1ng said carbureter chamber, said carbureting chamber and supply passage being formed by complementary separable shells, and means for securing said shells together, substantially as set forth.

27. In a carbureter, the combination with fuel supply means, of a carbureting chamber of circular cross-section, an air. supply passage, a heating jacket, and a discharge 1 pipe for the mixture arranged concentrically with respect to each other, said carbureting chamber, air passage and heating jacket eachformed by complementar separable shells, and a central stayrod or securing said shells together, substantially as set forth.

Witness my hand in the presence of two subscribing Witnesses. v

HERBERT MGGORNACK.

Witnesses:

SAML. MARSHALL,

TIE OBRIEN. 

